IF you should chance some day to take a short trip to the planet Saturn, which is scarcely more than 800,000,000 miles from here, you would experience at its aspect an indescribable astonishment that would certainly bear no approach to any like feelings that you have ever experienced on earth. Just imagine an immense globe, not only of the size of ours, but of as great a volume as 864 earths heaped up together I It whirls around on its axis with such velocity that, notwithstanding its size, it accomplishes its daily revolution in about ten hours. On a plane with its equator, and at about 20,000 miles distance, an immense and comparatively thin ring completely encompasses it. This ring is, in its turn, surrounded by a second ring, and the latter by still a third. Now this system of multiple rings is scarcely 300 miles in thickness, While it measures 37,lJOO miles in breadth. The rings are not stationary, but move in a circle about the planet, and with a velocity greater than that of the planet itself. But the domain of the Saturnian world does not end here; for, beyond the ring, are observed eight moons circulating in the heavens around this strange system. The nearest of these satellites is separated from the exterior ring by a distance of 37,000 miles; the farthest follows an orbit which is about 2,700,000 miles from the center of the planet. Saturn, then , commands a world which measures no less than 6,000,000 miles in diameter, that is to say, 18,000,000 miles in circumference! This is a world by the side of which the earth cuts a very modest figure; and Micromegas was very excusable in tak- THE WONDER OF THE WORLDS. ing our globe for a celestial mole-hill, when, leaving Saturn, he passed in the neigh borhood of our abode. Its years are thirty times longer than ours; its seasons each lasts seven years and four months, and they are marked by diversities that are sensibly like those that distinguish our own. A regenerating spring succeeds a rigorous winter, and a summer and autumn there exhibit their flowers and fruits. But the phenomenon which attracts most attention to this world is the gigantic ring that completely encompasses it. For a long time it was impossible to ascertain the nature of this appendage, which is unique in the whole planetary system. Galileo, who was the first to see on each side of Saturn something brilliant, but the form of which he could not dis tinguish, was .greatly amazed at such a sight. He announced it at first, under an anagram, in w hich Kepler himself could recog-nize nothing; and, as he had done in the case of Ven us, in hiding his discovery he gave himself the time to bring it to a successful i^ue. In awaiting a better name, he called Saturn tri-corps. “When I observe Saturn,” wrote he later to the ambassador of the Grand Duke of Tuscany, “the central star appears to be the largest; two others, one situated at the east and the other at the west, on a line which does not coincide with the zodiac, seem to touch it. These are like servants who are aiding old Saturn to perform his journey, and toM ever remain at his side. With a telescope of the lowest power, the star appears oblong and olive-shaped." But the industrious astronomer looked in vain. He was not favored in his researches as he had been in former ones. At the time when Saturn's rings are turned towards us edgewise, they are invisible on account of their thinness. On a certain evening, Galileo, finding it absolutely impossible to distinguish anything on each side of the planet where some months before he had observed the two luminous objects, was in complete despair, and made up his mind that the lenses of his telescopes had deceived him. Greatly discouraged, he no longer bestowed his attention on Saturn, and died without knowing that the rings existed. Later on, Hevelius in a like manner declared that all labor was being lost there, and it was only in 1659 that Huygens, the true discoverer of the ring, gave the first description as well as the first explanation of it. To the contemporaries of Galileo, Saturn was a bowl with two handles (ansiE), and, again, a mrdinal's hat. Later still, it was likened to a soap-ball in the middle of a barber's dish. In the middle of the eighteenth century, Maupertuis con * Translated from the Journal des Connaissancei UtUes tOt the Scibn- TlFio american. jectured that the ring was merely a comet's tail rolled like a turban around the Saturnian globe! Toward the end of the same century, Du Sejour wrote his “ Essay on the Phenomena relative to the Periodical Disappearances Qf Saturn's Ring,” in which he gave theoretically the time of the ring's rotation. He offered his work to Voltaire with the following graceful dedication: “Sir, be pleased to receive the history of a respectable old man upon whom attention will be bestowed on earth so long as wisdom shall be honored among men; his forehead is adorned with an immortal crown, and he enlightens us and exhibits to us one of the most singular phenomena of nature. This old man is Saturn, and I make haste to name him, for fear that another one might be designated whose portrait you) modesty would prevent you from recognizing. May this analogy merit on your part a favorable reception for my work.” Without the last remark, Voltaire himself, and better than any one, might have supposed, in fact, that Saturn was entirely foreign to the dedication. After Jupiter, Saturn is the largest of all the planets, its mean diameter being 73,000 miles, or, in other words, its diameter is to that of the earth as 9 to 1. Its time of revolution around the sun, which fixes the length of its year, is twenty- nine years one hundred and sixty-six days and twenty-three hours. This planet passes over one degree in thirty days, and a sign of the zodiac in two years and a half. As for the time of rotation of so enormous a planet around its axis, it is accomplished with prodigious rapidity, for the length of one of Saturn's days is no more than ten and a half hours. The swiftness of this movement has produced a considerable flattening at its poles, and which Bessel has estimated at a tenth of the total length of thc planet's equatorial diameter. The calendar of this strange world embraces no less than twenty-five thousand days to the year ! When Saturn is observed with the telescope, the globe is seen to be marked with bands that are alternately dark and brilliant; these being no wider than Jupiter's, but less easily perceived. The most constant of all is the large grayish belt which covers the equatorial zone. This is surrounded at the north and south by other smaller ones, whose chang. ing forms leave no doubt as to their atmospheric origin. The illustrious Sir William Herschel had remarked that the direction of these belts, like their form and even their color, is variable; and he did not always find them parallel to the ring, for he measured inclinations that were as much as fifteen degrees. The belts of to day would often differ from those of yesterday; and he considered these changes as certain indices of Saturn's atmosphere. These belts do not extend up to the poles. He also perceived in the changing tints of the polar regions, marks of the variation of temperature at the surface of the planet. These regions were less whitish in proportion as the sun bad the longer shone on them; but in winter, on the contrary, the pole was always more luminous. This phenomenon reminds one of the dif- ferent alternations of brightness tiiat the poles of Mars successively exhibit. “Whether or not,” says Humboldt, “this increase of intensity should be attributed to the temporaiy formation of ice and snows or the accumulation of clouds, it always exhibits effects that are produced on an atmosphere by variations of temperature." One of the most remarkable peculiarities of Saturn-s globe is its density, which is equal to three-fourths of that of water, and which decreases tcwards the surface. By reason of this circumstance, it is absolutely impossible for us to gain an idea of its material constitution and its molecular state; and we are not even allowed to decide whether or not the body of tlie planet is in a solid condition. For a long time past, some have believed that they resolved the problem by stating that the planet might indeed be composed of light materials, like pumice stone or wood. It has been remarked that the matter of which Saturn is composed is so light that if the globe were placed in the middle of an immense ocean it would float upon the surface of the water like an enormous fir-wood ball. If water forms an intcgi al part of the planet's ccmposition, it must exist therein only in the form' of snow and ice at the poles, and in a fluid state on the rest of its surface; from whence it may be corcludcd that the beings which inhabit it are of an entirely different structure from tho.se of the earth, and possess an organization adapted to the particular vital conditions which have been made for them. In the seventeenth century, an ecclesiastic of Avignon, named Gallet, endeavored to attract the attention of astronomers to the position of Saturn, and which he mid was eccentric to its ring; but his voice was unheard, and it was not till two centuries afterward, in the veal' 1817, that the fact was verified by Schwabe. In fact, the glebe of Satuin is not regularly concentric with the ring, but inclines a little toward the west. It is, thcuglit that these differences, which appear to be periodical, are caused by an oscillation of the ring's center of gravity around the central point of the planet. We on earth have the fault of considering those regions where individuals of our species could not live as radically uninhabitable. It is to hold a very sad opinion of the power of Nature, to believe that she constructed enormous globes at immeasurable distances and did not finish her work by placing inhabitants on them. If we should judge of the temperature of Saturn and even of that of Jupiter by thp remoteness of these two planets, according to our w?,y of jeing things, we should not hesitate for an instant to declare them uninhabited by reason of the cold that must pre vail upon them. We cannot imagine that men may exist who do not possess the same structure and the same needs as we.The distance from Saturn to the sun being more than nine times greater than that of the earth, the heat of the sun is ninety times less than it is here. Perhaps it is more condensed by an atmosphere there; perhaps that immense globe emits some heat itself; and perhaps the Saturnians would die of suffocation on the frozen seas of our North Pole. The conditions of life in J upiter, Saturn, and even in Uranus do not appear to differ any more from those of the earth than the condition of the terrestrial animal differs from that of the fish. “The inhabitants of Saturn,” said lluygens, in his time, “have no more eause than owls and bats to complain of the little light that they receive from the sun, for it is more advantageous and more agreeable to enjoy the glimmer of twilight, or the light which remains during night, than that which lights up the earth during the day.” The great Dutch astronomer added: “ The inhabitants of Saturn not only enjoy the same sights and the same pleasures that those of Jupiter do, but they also have more beautiful ones, because of their five moons as well as because of the beautiful aspect of the ring that they see day and night. On Saturn, only the planet Jupiter is seen, and this, for its inhabitants, is what Venus is for us." Fontenelle, who was always so ingenious in determining the conditions of existence in the planetary worlds, expresses himself thus in regard to Saturn: “We would be much astonished to see over our heads at night that great ring, which would extend as a half-circle from one end of the horizon to the other, and which, reflecting the light to us, would produce the effect of a continuous moon. . . . However this may be, the people of Saturn are pretty unfortunate, even with the help of the ring. It gives them light. but what a light at the distance it is from the sun ! The very sun, which they see a hundred times smaller than we do, is for them only a small pale white star with but little brightness and heat; and should you place them in the coldest of our countries—in Greenland or Lapland—you would see them sweat great drops of perspiration and expire of heat ! If water they had, it would not be water for them, but a polished stone, marble; and spirits of wine, which never freezes here, would there be as hard as our diamonds." After having taxed the men of mercury with folly by excess of vivacity, because of their proximity to the sun, Fontenelle treats those of Saturn as phlegmatic for the contrary reason. The inhabitants of such a world must assuredly differ strangely from us, from every point of view. The specific lightness of Saturnian substances and the density of the atmosphere will have led vital organization m an extra-terrestrial direction, and the manifestations of life will have been produced and developed there under unimaginable forms. To suppose that nothing is fixed there, that the planet is liquid, that the living beings, in a word, are gelatinous, and that everything there is unstable, would be without doubt going beyond the limits of purely scientific induction. But it is beyond all dispute that this, of all the worlds of the system, is the one that approximates nearest such a state. The conditions of gravity are not only strange there, but they even vary from one latitude to another. On account of the velocity of rotation, gravity is lessened one-sixth at the equator, so that while, in the polar regions, objects weigh more than they would upon the earth, at the equator they weigh less. On our globe a falling body passes through a space of 16 feet the first second of its fall, and on Saturn 17'5 feet in polar latitudes, but only 14'8 feet in the equatorial regions. If Saturn only revolved two and a half times more rapidly, objects would no longer have any weight at all in those regions! Moreover, the contrary attraction of the ring further diminishes the weight in a notable proportion, and there is a zone between the interior ring and the planet where bodies are attracted equally from above and below. It does not require a very great effort of the imagination to assume that, if an intermediate atmosphere permits it, the aerial inhabitants may enjoy the faculty of flying as far as the rings. Do they dwell in atmospheric regions? Is Saturn an aerial world whose natives live seated upon cloud thrones, as was Olympus in nlythologic times, and where formerly reigned Saturn himself, Jupiter, Mars, Venus, and the whole court divine? Had tlir Humphry Davy penetrated the secrets of heaven when he gave the following curious description of the inhabitants of the planet under consideration? "These gigantic beings of an indescribable form,” says he, “ appeared to me to be provided with a system of locomotion analogous to that of the sea horse, but their movements were effected by the aid of six membranes, which they made use of as if they had been wings. Their colors were beautiful and varied, especially azure and rose. The forward portion of their body was provided with a great number of coiled and movable tubes, whose form reminded me a little of elephants' trunks. ... I experienced an unusual fear when I saw one of them take flight and rise toward the -clouds. . . . These beings live in the atmosphere. Their degree of sensibility and happiness greatly surpasses that of terrestrial beings; they are endowed with numerous senses; they have subjugated the forces of nature, and, owing to the density of their atmosphere and the specific gravity of their planet, they have been enabled to determine all the movements of the solar system with precision. The first comer among them might be able to tell where the terrestrial moon was by caleulation, without having seen it. Their minds are in a constant state of activity, and this activity is a perpetual source of enjoyment. They feed on fluids and live upon their clouds, which they manage like aerial chariots,” etc., etc. It is an indisputable fact that the world of Saturn is more aerial than ours, and that its atmosphere plays an important part, whilo the density of bodies there is very slight. This atmospheric pressure would be indeed tremendous were the Saturnian world as cold as its distance would seem to indicate, but it may be greatly diminished by heat. Now, telescopic observations lead us to believe that in fact the quantity of heat there is greater than -that which would result from the distance from the sun. But what is the nature of those marvels, the rings? Are they solid, liquid, or gaseous? They are, we have said, I broad and flat (like a circle of cardboard placed around a : terrestrial globe), and touch their planet at no point. Strange i equatorial girdle! Sometimes they show themselves to us j edgewise (this happened in 1878), and their thinness causes them to disappear entirely and makes the Saturnian globe appear as if only traversed by a thread.j Whether they be three in number or more, they cannot be .solid, and resemble, for instance, flat circles of greater or less width. The constant variations of the planet's central attraction. combined with that of the eight satellites, would ' not only have dislocated and broken them if they had I been able to form such a solid structure, but would have, in 1 advance, absolutely prevented such a formation. It would be easier to admit that they are liquid, for in this case their elasticity might be able, so to speak, to lend itself to all the vagaries of attraction; but in this case there would be a transformation of motion into heat, a diminu- , tion of motion and a positive fall upon the planet. Are they then gaseous? The transparency of the inner one might give credence to such a belief; but such, however, ' is not the fact. What, then, ought we positively to think of their nature? ' This is a problem in regard to which I entered into a mathematical discussion in 1867, and which led me to the conclusion that the only system of rings that can exist is a system composed of an infinite number of distinct particles revolving around the planet with different velocities, according to their respective distances. These particles, I added, may be arranged as a series of narrow rings, or each one of them may move irregularly. No refraction being observed upon the limb of the planet seen through the interior ring, it follows that this ring is not gaseous and that the rays do not pass through a gas. The other two rings may be of the same nature, but formed of such a multitude of particles that it is impossible for them to be transparent. According to my calculations, the particles which form the transparent ring must revolve about the planet in a period included between 5 hours and 50 minutes and 7 hours and 11 minutes, according to their distance from Saturn, the nearest zone revolving most rapidly; those which compose the large bright ring must revolve in periods comprised between 7 hours and U minutes and 11 hours and 9 minutes, also according to their distances; and finally, the exterior limit of this singular system must accomplish its revolution in 12 hours and 5 minutes. But the eight satellites which gravitate outside of the rings must be the cause of considerable perturbations in these motions, and it is perhaps to the unstable equilibrium that they keep up that is due the preservation of the Saturnian appendage; for it seems that, without their support externally, the unavoidable frie- tions and shocks that take place would at every instant necessarilv put the stability of this strange crown in jeopardy. Supposing the ring solid, Laplace had estimated 10 liours and a half as the time of revolution, and Sir William ller- schel believed that he had observed a movem?'1t of the same duration. But this period can only pertain to a zone situated m the upper quarter of the broad central I'ing, and not to the rest of the system. In fact, it has not been verified by modern observations. The ring could revolve as one entire piece only if, its mass being enormous, its parts should obey this mass rather than the attraction of the planet. Perhaps it increases in thickness up to near the middle of the eentral ring. This mysterious annular system appears to be slowly nearing the planet. Perhaps it is progressively descending spirally thereupon like a whirlwind, and perhaps astronomers of future ages will witness the grand speetacle of the sinking down of the rings upon the Saturn ian world. Let us complete this study by transporting ourselves in imagination to some point of Saturn's globe. From there let us cast a glance at the appearances that the celestial dome must present during day and night. If we start from either pole and proceed as far as the 63d degree of latitude, we shall travel over every spot of the Saturnian hemisphere where the triple ring is never visible. The satellites alone rise above the horizon and exhibit the varied aspect of their phases to the spectator. The Satur- nians of these regions, provided they have not traveled, do not know their world as well as we do. Leaving this latitude, the annular system begins to be visible. But it is only during the two seasons, spring and summer, that the face of the rings turned toward the hemisphere where we are situated receives the sun's rays and illumines the planet's nights by reflection. During the day their arches send only a feeble light, which is doubtless analogous, as regards color and luster, to that of the moon when visible in broad daylight. The form and extent of the immense luminous arches vary, moreover, according to latitude. On leaving the 63d degree and advancing toward the equator, they are observed to rise more and more above the horizon. At first it is a small portion of the exterior ring. then this ring in its total width. In mean latitudes of 45” there are perceived the two first rings, and between them the space by which they are separated. In proportion as we descend toward the equatorial regions, the entire system becomes visible; but , at the same time, the visual rays having a more oblique direction, the rings diminish in apparent breadth. At thevery equator they are no longer visible except by their interior edge. This edge then looks like an immense luminous ribbon extending from east to west, and passing through the zenith. What a marvcJ is this ring seen from Saturn itself, and how pleasant it would be for some artistic person to take a short trip thither! Such is this vast Saturnian world, which is wandering on at more than eight hundred millions of miles from here, a distance at which our abode becomes nothing more than a point visible in the telescope only, and like a black spot, which from time to time crosses the sun.
This article was originally published with the title "The Wonder of the Worlds" in s , , 3061-3062 (January 2012)